The present invention relates to a block copolymer type compatibilizing agent for a blend resin containing a vinyl-based polymer and a condensation type polymer, and a method for production thereof.
The present invention relates to a functional block copolymer for imparting functions such as a ultraviolet ray absorbing ability and flame retardant property to a synthetic resin and a method for production thereof.
In general, a synthetic resin is required to have various functions depending on the use and the using condition, and therefore, a conventional synthetic resin is modified to impart novel functions to the resin by adding functional monomers or polymers into the resin. As an example, for prevention of ultraviolet interference on a synthetic resin, a ultraviolet absorber such as a benzophenone derivative, benzotriazol derivative or the like is added to prevent ultraviolet ray-induced degradation of the synthetic resin itself and to impart weatherability to the resin.
For imparting flame retardant property, antimony oxide, phosphorus compounds or halogenated compounds is also conventionally used.
In addition to the addition of such functional monomers or polymers, there is a blend resin method as a method widely used for improvement of the properties of a synthetic resin. The blend resin method is a method of mixing two or more polymers to form a synthetic resin so as to take in excellent properties of each polymer for improvement of the characteristics of the resin. For forming the blended resin, it is important that these polymers have compatibility to each other since the forming is in general conducted after mixing and melting them. When the compatibility between the polymers is poor, the blended resin sometimes can not manifest the expected characteristics thereof and some modifiers for compatibility or compatibilizers should be added to the polymers.
Though it can also be supposed that a condensation-type polymer (for example, ester-based polymer) and a vinyl-based polymer are combined and blended, when these polymers are incompatible or partially compatible, suitable compatibilizers are required.
Regarding associated techniques, there is known a technique for copolymerization of a condensation-type polymer (for example, polyester-based polymer) and vinyl-based polymer (Japanese Patent Application Laid-Open (JP-A) No. 59(1984)-27908), and since this block copolymer itself was used as a thermoplastic resin being subjected to heat forming, the characteristics thereof were determined by the composition and properties from each polymer, and, further, it was difficult to regulate the composition at will and the copolymer resin was expensive due to the production method.
Further, there is a case in which whole resin may have the function through the resin and a case in which only the surface layer of the formed resin article may have the special function. Regarding the former case, compatibility is required for mutual solution of blended polymers or for micronization and dispersion of the polymers in the micro structure of the resin, and for this reason a compatibilizing agent is utilized in the melt-blend of incompatibilizing polymers.
As an example of the latter case, there is a surface antistatic agent which lowers the surface electrical resistance and impart electrical conductivity. Regarding this technique, Japanese Patent Application Publication (JP-B) No. 5(1993)-41668 suggests an antistatic agent comprising a block copolymer obtained by introducing a hydrophilic vinyl-based segment and a hydrophobic vinyl-based segment using a polyazo compound as a polymerization initiator, in which electrical static charge of the resin is prevented by producing surface electrical conductivity by the hydrophilic segment.
Further, in relation to the present invention, Japanese Patent Application Publication (JP-B) No. 5(1993)-41668 suggests an antistatic agent for imparting electrical conductivity to a vinyl-based synthetic resin obtained by using an azo group as a vinyl polymerization initiator and by block-polymerizing vinylmonomers in turn, to form a hydrophilic segment and hydrophobic segment in a polyazo compound.
Also, there is known a technique in which a polycarbonate copolymer which is obtained by copolymerization with a styrene-based polymer and subsequent modification is used as an optical lens, and the optical distortion thereof is improved (Japanese Patent Application Laid-Open (JP-A) No. 61(1986)-19630).
Regarding the above-mentioned ultraviolet absorbing property, the above-mentioned lower-molecular ultraviolet absorbing agent is conventionally added in a small amount (for example, from 0.02 to 0.1% (by weight)). However, even if this agent is added in a large amount in the process of forming of a synthetic resin, it is vaporized in the step of heat-melting, therefore, the yield thereof is low and the synthetic resin is unpreferably expensive.
Also, as a higher-molecular ultraviolet absorbing agent, random copolymers formed of styrene and a vinyl-based ultraviolet absorbing compound are known. Though the higher-molecular ultraviolet absorbing agent is effective for prevention of the vaporization in heat-melting, its compatibility with a resin to be added becomes a problem. For example, regarding the above-mentioned ultraviolet-absorbing polymer comprising styrene, because the polymer has poor compatibility with a polycarbonate, the homogeneous dispersion of the polymer can not be obtained, so that synthetic resins in which the polymer can be utilized are limited.
Also regarding flame retardant property, a phosphorus compound is utilized from the viewpoint of stability and transparency for a transparent synthetic resin. However, in this case, such compatibility that enables uniform dispersion in the resin is necessary.
In general, as functions to be manifested uniformly in the resin, there are flame retardant property, impact resistance, radiation resistance and the like. For manifesting these functions, it is necessary that functional components manifest compatibility to the synthetic resin after melting and are dispersed uniformly in the resin.
Further, in the point of functionalization of the surface properties and conditions of a synthetic resin, there are required ultraviolet absorbing property, pollution resistance, antibacterial property and the like in addition to antistatic property and electrical conductivity. In this case, uniform dispersion within the resin is not necessarily required, rather, it is required a nature that these function imparting components gather on the surface in a cooling process after melting in forming. Therefore, because of these functions, necessity occurs to regulate distribution of the functional components in the resin.
On the other hand, also regarding polymer components in the synthetic resin, there is a case in which not only a vinyl-based polymer but also a condensation-type polymer, particularly an aromatic ester-based polymer is required to have these functions, and further there is a case in which a specific resin is required to comprise a material endowed with these specific functions. Therefore, when a function modifying agent is used, compatibility and uniform dispersion property between the specific resin and the modifying agent become problems.
Further, as described-above, when a mixture of a polycarbonate and a styrene-based polymer is used as a optical lens, the birefringence thereof is a problem. For this use, there is used a resin having negative optical anisotropy opposite to that of a polycarbonate, for example a resin having lowered optical aeolotropy by copolymerization with a polystyrene as described above. However, if a polycarbonate and a polystyrene are not copolymerized but can be mixed in a constant ratio and the structure thereof can be micronized differing from the above-mentioned method, it is expected that optical isotropy can be provided and birefringence can be solved by such a simple means as mixing, and, a compatibilizing agent will be required here.
Further, since polycarbonate resins are excellent in translucency, strength, impact resistance, heat resistance and the like, they are used as a substrate material of a laser compact disk. A polystyrene is used for a case accommodating this disk, and the compact disk is often discarded simultaneously together with the case. And, when such discarded plastic materials are recovered and reused, the polycarbonate and polystyrene are molten simultaneously and metal parts and the like are separated from the melt before the melt is formed into some article by injection molding, extrusion or the like and the article is utilized as a blend product of polycarbonate-polystyrene. However, the compatibility between a polycarbonate and a polystyrene is poor, and the blend product thereof suffers from lowering of mechanical strength and impact strength and can not be handled in the same manner as a formed article comprising only a polycarbonate, therefore it is required to modify the blend product of polycarbonate-polystyrene.
The object of the present invention is to provide a compatibilizing agent which can enhance the compatibility between polymers in a blend resin having any blending composition at will and a method for producing the same.
Further, another object of the present invention is to provide a production method in which a component of a compatibilizing agent can be prepared from a constitutional component of a blend resin to which the compatibilizing agent is added.
Further, another object of the present invention is to provide a polymer for imparting the above-mentioned functions to a condensation-type copolymer, particularly a synthetic resin comprising an aromatic ester-based polymer and a vinyl-based polymer, and a method for producing the same, and by utilizing them, such a functional polymer and a modifier using the same are provided.
The present invention provides a compatibilizing agent for a resin obtained by blending a condensation-type polymer and a vinyl-based polymer. Namely, by using as a compatibilizing agent a block copolymer composed of a polymer compatible with the aforesaid condensation-type polymer and the other polymer compatible with the vinyl-based polymer, the compatibility between the condensation-type polymer and the vinyl-based polymer is enhanced in mixed condition in blending.
Namely, the compatibilizing agent of the present invention is a condensation-type vinyl-based block copolymer obtained by previously incorporating a segment of a condensation-type polymer into a polyazo compound to obtain a macroazo polymerization initiator and by polymerizing a vinyl-based monomer at the azo group site.
This block copolymer has a structure which comprises a segment of the condensation-type polymer and a segment of the vinyl-based polymer in a straight chain. Then, when the compatibilizing agent is added to a melt in polymer-blending, the block copolymer acts on the molten mixture of the condensation-type polymer and the vinyl-based polymer having poor solubility each other and the condensation-type polymer segment is dissolved in the condensation-type polymer and the vinyl-based segment is dissolved in the vinyl-based polymer, therefore, the mutual dispersing property of the condensation-type polymer phase and the vinyl-based polymer phase, namely compatibility is improved via the block copolymer, and micronization and compactness of the micro structure of the resulting resin are improved.
Further, in the present invention, there is provided a block copolymer comprising either a condensation-type polymer or vinyl-based polymer segment and a vinyl-based function imparting polymer segment in a repeating unit in the chain, and this block copolymer can be utilized as a main component or a part of components of a synthetic resin to manifest functions due to the function imparting segment in the synthetic resin.
The condensation-type or vinyl-based segment which the block copolymer has can be selected to manifest compatibility with a polymer in a resin to be added, and consequently the block copolymer is uniformly dispersed in the resin, therefore, the block copolymer can also be used as an additive for the resin.
The block copolymer of the invention is formed by block-copolymerizing a radical-polymerizable monomer for imparting functions to a polyazo compound comprising the segment of a condensation-type or vinyl-based polymer and an azo group in a repeating unit.
Further, as the other method, the block copolymer is also formed by block-copolymerizing a radical-polymerizable monomer for imparting functions to a polymeric peroxide comprising the segment of a condensation-type or vinyl-based polymer segment and a peroxide group in a repeating unit using the peroxide as a polymerization initiator.
The monomer for imparting functions becomes a function imparting segment by block-copolymerization, and the copolymer manifests functions, in the blend resin added, corresponding to the inherent natures which the monomer have. The example of such functions includes flame retardant property, heat resistance, radiation resistance, ultraviolet ray absorbing property, antistatic property, surface electrical conductivity, oxidation resistance, pollution resistance, antimicrobial property and the like.
In the block copolymer of the present invention, there is also used a segment which is obtained by polymerizing a monomer having lower cohesive energy to the third block segment together with the condensation-type or vinyl-based polymer segment and the function imparting polymer segment. This segment having lower cohesive energy is a polymer having lower cohesive energy than the condensation-type or vinyl-based polymer segment or the main constituting component polymers of the synthetic resin.
Since the segment having lower cohesive energy migrates to the surface of the block copolymer and coheres after melt-setting of the block copolymer, the function imparting segment in the chain of the block copolymer moves to the surface layer together with the migration of the segment having lower cohesive energy, and is condensed in the layer. As a result, the functions work in concentration in the resin surface layer. As functions required in such a surface layer, ultraviolet ray absorbing property, antistatic property, surface electrical conductivity, oxidation resistance, pollution resistance, antimicrobial property and the like are important.